Update 18 July 2018:
The first OTA Over the air ROM rolled out on the Tuesday 17, July. While this was a milestone moment for those who had the Lineage ROM on the Xiaomi Mi A1 there was a major hiccup in the release.
The first problem was the OTA downloads were extremely slow. When it finally made to the user’s phones the update failed.
The telegram group for MiA1 was flooded with messages from MiA1 users and the issue is expected to be resolved in the next build. There is a build every Tuesday.
The current work around is as under ;
Please note this option works when coming from the previous week’s signed Lineage official ROM
Step 1: Download the latest ROM the July 17 version from here
Please note the download may take a long time. On my 10 Mb line it took a couple of hours!!! Once downloaded copy the ROM on to your phone.
Step 2: Reboot to recovery
Please DO NOT WIPE ANYTHING
Step 3 : Flash the latest lineage official ROM, downloaded in Step # 1
Step 4: Reboot to recovery again
Step 5: Flash Mind the Gapps
Step 6: Flash Magisk
Step 7: Reboot
The official lineage ROM for the Xiaomi MiA1 was released on 10 July 2018. The release was eagerly awaited by thousands across the world. The only problem was that when it rolled in the user were in for a surprise… a slightly unpleasant surprise. The flashing of the ROM required a whole new set of steps and there were problems at each stage. I consider myself as quite an expert at flashing the unofficial ROM‘s..at least on my MiA1 and had even built a ROM for the MiA1 based on code from GitHub. but I had some real problems this time. After a lot of false starts I finally managed to get the official ROM on my phone.Given below are the steps I took. You would need adb and fastboot on your PC to achieve all this. In case you do not have the same please click here and also enable phone developer options.
Step 1:Download and copy the files mentioned below to your phones Downloads folder. Copy the Boot recovery.img file to the adb folder.
Step 2: If coming from a the unofficial Lineage ROM get to the boot loader screen.
Power off phone.
Hold Power + Volume down button.
When the phone vibrates release. You should be in the Boot loader screen.
Step 3: From your PC go to the folder where you have adb and type
fastboot boot boot-recovery.img
Within seconds the recovery image will be loaded on to you phone and you should be in the TWRP screen.
Step 4: Wipe cache, data and system
5 . Flash Lineage Official
6. Flash TWRP by CosmicDan file TWRP-Installer-3.2.1-with-Tissot-Manager-2.3.zip
This TWRP will install itself on both A and B partitions of your phone.
7. In TWRP Reboot to Recovery
8. Flash Magisk 16.6
9. Flash Mind the gapps
10. Reboot System and wait for the phone to boot up.
Download the files from here.